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Inter-ring gas pressure and piston ring motion are considered important for the control of oil consumption, particulate emissions, and reduced friction. For this reason, inter-ring gas pressure was measured on a diesel engine. Two different ring pack configurations were tested (positive and negative twist second rings). A significant difference in measured inter-ring pressure was observed. The measurements were compared to the predictions of a cylinder kit model with favorable results. Predictions showed that the observed difference between measured inter-ring pressures is caused by a significant difference in ring motion. The reasons for these differences are explained in this paper.

Piston ring pack performance is very critical to diesel engine blow-by and oil consumption. As structural analysis tools such as Finite Element Analysis and Boundary Element Analysis can be used to ensure the piston structural integrity, cylinder kit dynamics models are being used to predict power cylinder system performance. In this paper, detail comparisons of engine test measurements and model predictions under various operating conditions and with different ring pack configurations are presented. The cylinder kit model used for this paper is one out of six different models that were evaluated.